000 AXNT20 KNHC 230551 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU OCT 23 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 26W S OF 14N MOVING W 5-10 KT. THIS WAVE IS NOT PARTICULARLY WELL-DEFINED...AND DRY AIR EMBEDDED WITHIN THE BASE OF AN UPPER TROUGH IN THE E ATLC N OF 11N E OF 38W IS SUPPRESSING CONVECTIVE DEVELOPMENT NEAR THE WAVE. HOWEVER...CIMSS WAVETRAK PRODUCT DEPICTS A WEAK AND DISORGANIZED AREA OF LOW LEVEL COUNTERCLOCKWISE CIRCULATION PRESENT NEAR WAVE AXIS. ISOLATED MODERATE CONVECTION IS OCCURRING WITHIN 150 NM EITHER SIDE OF WAVE AXIS S OF 11N...LIKELY BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR THE ITCZ. A TROPICAL WAVE IS ALONG 52W/53W S OF 20N MOVING W 5-10 KT. A RECENT ASCAT PASS DEPICTS COUNTERCLOCKWISE CURVATURE IN THE SURFACE WIND FIELD IN THE VICINITY OF THE WAVE AXIS. THIS WAVE IS NEARLY ALIGNED WITH A SURFACE TROUGH TO THE NORTH THAT EXTENDS FROM 30N50W TO 22N52W. THIS WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THIS MOISTURE IS BEING DRAWN NORTHWARD OVER THE E PORTIONS OF AN UPPER TROUGH OVER THE CENTRAL ATLC FROM 17N-31N BETWEEN 48W-63W. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF WAVE AXIS S OF 14N...LIKELY BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR THE ITCZ. A TROPICAL WAVE IS ALONG 82W S OF 18N MOVING W 10-15 KT. THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE...AS WELL AS A MAXIMUM IN LOW LEVEL COUNTERCLOCKWISE CIRCULATION BASED ON CIMSS WAVETRAK PRODUCT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OCCURRING WITHIN 210 NM EITHER SIDE OF WAVE AXIS FROM 12N-15N. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS FROM 16N-19N BETWEEN 80W-83W...WHICH IS LIKELY BEING ENHANCED BY UPPER LEVEL DIFFLUENCE TO THE W OF AN UPPER HIGH IN THE CENTRAL CARIBBEAN NEAR 17N79W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 10N22W 8N36W 11N50W 9N61W. IN ADDITION TO CONVECTION ASSOCIATED WITH TROPICAL WAVES... SCATTERED MODERATE CONVECTION IS FROM 3N-9N BETWEEN 10W-17W... AFFECTING W PORTIONS OF GUINEA-BISSAU. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF AXIS BETWEEN 19W-23W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF AXIS FROM 29W-50W. SIMILAR CONVECTION IS FOUND WITHIN 150 NM N OF AXIS BETWEEN 55W-61W. ...DISCUSSION... GULF OF MEXICO... MUCH OF THE GULF IS COVERED BY INCREASING SOUTHWESTERLY FLOW ALOFT...AS A VIGOROUS UPPER TROUGH OVER THE SOUTHERN PLAINS OF THE CONUS CONTINUES TO APPROACH THE GULF. AT THE SAME TIME...DEEP MOISTURE IS ROTATING NORTHEASTWARD AROUND AN UPPER HIGH IN THE CENTRAL CARIBBEAN NEAR 17N79W. UPPER LEVEL DIFFLUENCE TO THE N OF THIS UPPER HIGH IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE E GULF S OF 27N E OF 87W...AFFECTING S PORTIONS OF FLORIDA AND W CUBA. THIS ACTIVITY IS BEING ENHANCED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH THAT EXTENDS FROM A 1010 MB SURFACE LOW OVER NE BELIZE NEAR 18N88W TO THE N YUCATAN PENINSULA NEAR 22N87W TO THE SE GULF NEAR 24N83W. COMPUTER MODEL GUIDANCE SUGGESTS THAT STRONG UPPER LEVEL DIVERGENCE SE OF A MID/UPPER-LEVEL WIND SPEED MAXIMUM ROTATING AROUND THE AFOREMENTIONED VIGOROUS UPPER TROUGH WILL HELP TO CONCENTRATE THE SURFACE TROUGH AND SURFACE LOW OVER THE NE GULF...WITH A LOW EXPECTED IN THE NE GULF OVER THE NEXT DAY. ALSO...A COLD FRONT ASSOCIATED WITH THE VIGOROUS UPPER TROUGH IS APPROACHING THE NW GULF...WITH INCREASED NORTHERLY SURFACE WINDS IN THE WAKE OF THE FRONT. ADDITIONALLY...A SURFACE TROUGH OVER THE W GULF EXTENDS FROM 28N95W TO A 1011 MB SURFACE LOW NEAR 23N94W TO 21N92W. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS RESULTING IN ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH. CARIBBEAN SEA... A SURFACE TROUGH IS OVER THE W CARIBBEAN AND EXTENDS FROM A 1010 MB SURFACE LOW OVER NE BELIZE NEAR 18N88W TO THE N YUCATAN PENINSULA NEAR 22N87W TO THE SE GULF NEAR 24N83W. BROAD LOW LEVEL CONVERGENCE AROUND THESE FEATURES...COMBINED WITH AMPLE DEEP LAYER MOISTURE AND UPPER LEVEL DIVERGENCE TO THE W OF THE UPPER HIGH IN THE CENTRAL CARIBBEAN NEAR 17N79W...IS RESULTING IN ISOLATED MODERATE CONVECTION IN THE NW CARIBBEAN FROM 21N-23N BETWEEN 82W-87W...INCLUDING W CUBA. ALSO...NUMEROUS MODERATE/SCATTERED STRONG CONVECTION FROM 16N-19N BETWEEN 80W-83W IS LIKELY RESULTING FROM THE INTERACTION OF UPPER LEVEL DIFFLUENCE W OF THE UPPER HIGH AND THE TROPICAL WAVE ALONG 82W S OF 18N. ALSO...SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER NICARAGUA AND COSTA RICA IS IMPACTING THE NEARBY CARIBBEAN WATERS. THIS CONVECTION IS BEING ENHANCED BY GREATER INSTABILITY OVER HIGHER TERRAIN. TO THE E OF THE AFOREMENTIONED UPPER HIGH...DEEP LAYER DRY AIR AND STABLE ATMOSPHERIC CONDITIONS ARE INHIBITING DEEP CONVECTION OVER THE E CARIBBEAN. ATLANTIC OCEAN... THE FLOW AROUND THE UPPER HIGH IN THE CENTRAL CARIBBEAN NEAR 17N79W IS BRINGING DEEP MOISTURE INTO THE SW ATLC...WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS S OF 27N W OF 71W...AFFECTING S PORTIONS OF FLORIDA AND E CUBA. FARTHER TO THE E...A DEEP LAYER TROUGH IS OVER THE CENTRAL ATLC FROM 17N-31N BETWEEN 48W-63W...AND IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 30N50W TO 22N52W. DEEP LAYER MOISTURE OVER E PORTIONS OF THE DEEP LAYER TROUGH IS ENHANCING SCATTERED MODERATE CONVECTION FROM 22N-24N BETWEEN 50W-52W. FARTHER TO THE E...AN UPPER RIDGE AXIS EXTENDS FROM 35N38W TO 24N42W TO 15N45W...AND AN UPPER TROUGH IS IN THE E ATLC N OF 11N E OF 38W. GENERALLY DEEP LAYER DRY AIR IS PREVENTING DEEP CONVECTION NEAR THESE FEATURES. ADDITIONALLY...A 1030 MB SURFACE HIGH IS CENTERED NEAR 38N22W...AND A SURFACE RIDGE EXTENDS FROM THIS SURFACE HIGH TO THE SW NEAR 16N40W...WITH SUBSIDENCE AND STABLE CONDITIONS AROUND THESE FEATURES RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE E ATLC. $$ COHEN